A toolkit of support libraries and Ruby core extensions extracted from the Rails framework. Rich support for multibyte strings, internationalization, time zones, and testing.

Protocol Buffers are Google's data interchange format.

Provides swappable XML backends utilizing LibXML, Nokogiri, Ox, or REXML.

A secure, non-evaling end user template engine with aesthetic markup.

Really simple JSON and XML parsing, ripped from Merb and Rails.

The fastest JSON parser and object serializer.

The Database Toolkit for Ruby

Ruby JSON Schema Validator

Type system for Ruby supporting coercions, constraints and complex types like structs, value objects, enums etc

A gem that provides a client interface for the Sentry error logger

Font Metrics Parser for the Prawn PDF generator

XML to Hash translator

A framework for building reusable, testable & encapsulated view components in Ruby on Rails.

Facebook OAuth2 Strategy for OmniAuth

Sunspot is a library providing a powerful, all-ruby API for the Solr search engine. Sunspot manages the configuration of persistent Ruby classes for search and indexing and exposes Solr's most powerful features through a collection of DSLs. Complex search operations can be performed without hand-writing any boolean queries or building Solr parameters by hand.

All the stuff that isn't good/big enough for a real library.

Get memory usage of a process in Ruby

As of version 0.6.0, only Microsoft Excel compatible spreadsheets are supported

Go faster, off the Rails

google-cloud-bigquery is the official library for Google BigQuery.